High BMI tied to better cardiac bypass results

The obesity paradox lives on: overweight and obese patients with multivessel Coronary Artery Disease seem to fare better after coronary artery bypass surgery than their normal-weight counterparts, the results of a new study indicate.

Dr. Patrick W. Serruys from Erasmus Medical Center in Rotterdam, the Netherlands, and colleagues determined the impact of body mass index (BMI) on 3-year outcomes of patients enrolled in the Arterial Revascularization Therapies Study.

Five hundred ninety-nine patients underwent coronary bypass intervention (percutaneous coronary intervention; PCI) that included placement of a stent to keep clogged arteries open, and another 604 patients underwent coronary artery bypass grafting (CABG), a more invasive procedure in which the blocked arteries are bypassed by implantation of a graft (usually a blood vessel taken from the patient's leg).

BMI had no effect on outcome in patients who underwent PCI with stent placement, the researchers report in the American Journal of Cardiology.

However, among patients who underwent CABG, those who were overweight or obese had a significantly better outcome - with longer survival rates without a major cardiac or cerebrovascular event - than did patients who had a normal BMI.

The better outcome in the overweight and obese patients assigned to CABG was due mainly to a lower rate of repeat surgical procedures than in the stenting group, the investigators report.

There are many theories to explain the so-called "obesity paradox," the team points out. Patients who are overweight or obese may have larger coronary arteries or different immune system responses, they suggest. The lean group may also include more patients with other underlying illnesses and more smokers.

The impact of BMI on outcomes after heart surgery remains controversial. Some studies have shown that patients with coronary artery disease and normal BMIs are at greater risk for complications and death after PCI than are those with a higher BMI. Others have shown that increased BMI portends a worse outcome after CABG but not after PCI.

"Currently, no definite conclusion can be obtained regarding the effect of BMI on outcome after PCI or CABG," Serruys and colleagues write.

SOURCE: American Journal of Cardiology, February 15, 2005.